Machines such as hydrogen-cooled generators or other machines which can be filled with gas are designed in such a way an inspection in the interior of the machine is not possible as long as the machine is filled with the hydrogen or with gas. Therefore, sampling of particles on the surface in the interior of the machine is currently hardly possible or possible only with difficulty.
However, in order to take pictures or to carry out sampling of particles on surfaces in the case of hydrogen-cooled generators or machines which can be filled with gas, multiple steps are required in order to remove the gas from the machine. First of all, the hydrogen has to be released from the machine and this is then purged with an inert gas, such as carbon dioxide or argon. After purging with the inert gas, the generator is filled with air. After filling with air, the generator is accessible and can be inspected. However, the duration of this process is comparatively long in the case of large generators. Experience shows that such an implementation of this process can account for more than eight hours. Furthermore, a certain time period must be added since the generator has to be cooled down after operation. Only after the generator has cooled down can this be opened in order to carry out corresponding operations such as inspections.
Furthermore, after completion of the inspection operations, a certain time period is again required in order to fill the generator with hydrogen. This can also last up to eight or more hours. Furthermore, a pressure test is usually carried out, for which one day has also to be taken into account. Therefore, a week-long shutdown can be assumed overall if after the pressure test a delay is additionally incurred as a result of rectification due to leakages.
It would be desirable to curtail this time.